Electric motor.



A. W. FORBES.

ELECTRIC MOTOR.

APPLICATION FILED JAN. 18. 1913.

1,237,248. Patented 14, 1917.

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' Z72, foz'rzey A. W. FORBES.

ELECTRIC MOTOR APPLICATION FILED JAN. 18, 1913.

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' Patented Aug. 14, 1917.

ALLAN W. FORBES, 0F WORCESTER, MASSACHUSETTS.

ELECTRIC MOTOR.

To all whom it may concern.

Be it known that .I, ALLAN W. Forums, a citizen of the United States,residing at Worcester, in the county of Worcester, State ofMassachusetts, have invented a certain .new and useful Improvement inElectric Motors, of which the following is a specification, referencebeing had therein to the accompanying drawings.

This invention relates to electric motors but more particularly to thoseof'the single phase induction type and means forv starting the same. i fe Heretofore single phase induction motors have generally been startedby means of 'devices which cause the magnetic flux to move aroundtherotor so as tgeross the conductors thereon, producing a flow in theseconduc-' tors which starts the motor. =();f these devicesth'e mostcommon are the split phase winding of which there are a number ofdifferent forms, and the shading pole.

In the present invention the fluxis made to move longitudinally of theshaft andrthe conductors on the rotor and the stator are placed at anangle with each other so' that the flux will cut the rotor conductors.This construction produces the same starting effeet in the motor but ismuch simpler in mechanical design and operation and has greaterelectrical efficiency than either of these earlier types, as will befully'understood from the detailed description followmg. p

Referring to the drawings,:-'

Figure l'is a vertical center section of one embodiment of the inventioncomplete.

Fig. 2, section on line 2-2 of Figill.

- Fig. 3, detail view, as will be lly described hereinafter. I

Fig. 4, diagrammatical view of one em-- bodiment of theinvention, aswill be fully described hereinafter.

Fig. 5, end-view of the rotor shown in Fig. 4.

/ Figs. 6, and 7 modified forms of the invention, as will be fullydescribed hereinafteri In the embodiment shown in Figs. 1-3 inclusive,.a rotor member 10 is mounted upon the shaft 11 which is supported bysuitable hearings in the frames '12 and 13. Between these frames andsecured thereto by bolts .14. is the stator 15 which is shown inperspective detailed in Fig. 3, a portion of the wall thereof being cutaway to disclose the pfthe invention, a second Specification of LettersPatent. Patented Aug. 14, 1917. Application filed January 18, 1913.Serial No. 742,881;

particular type of winding 16 therein.- The rotor in this embodiment 15preferably constructed of solid iron though it may be otherwise formedif desired, and" through this rotor core passes the insulated conductingrods 17 which form the winding of the same.

These rods are here seated in the core parallel to the axis of the shafton which the rotor is mounted. When this-arrangement of the rods 17 isused the winding 16 in the stator should preferably be. at an angle asshown in Fig. 3.

The connecting ring 18, preferably of copper or other-suitableconducting-material, which: is in electrical contact with the rods 1; ofthe core winding, is insulated from the core by the insulation 19. Thering 20 upon the opposite end of the core 10 is in electrical contactwith that end of the core instead of insulated therefrom, as was thering 18 biltotherw'ise is practically the same as this ring. 3

In order to /fully illustrate the principles embodiment of the inventionis diagrammatically illustrated in Fig. 4 of'the drawings. In thisembodiment two iron structures 21 and 22 are upon the shaft 23 and formthe rotor. These structures are similar to simple single phase'armatures and are provided with a winding 24, here shown of thesquirrel: cage type, which extends across between them, theextreniities'of the rods being secured to or in contact with theconnecting-rings 25. and 26 on the outer ends of the structures 21 and22 respectively.'

The structure 22 is provided with a second winding 27, also shown of thesquirrel cage type, and the. rods of this winding terminate in contactwith connecting rings 28 and 29 at the opposite ends of this structure.

Two stator windings 30 and 31 respec- I tively opposite the structure 21and 22 are preferably connected in series and set at an angle to eachother about these structures; These windings maybe of the concentratedtype as shown in Fig. 4, or distributed in'several slots as is shown inFig. 3. v The two wires connecting with the line are'designated 32 and33.

. .When the current enters the motor, it will flow equally in windings30 and 31. This will induce currents in both rotor windings 24 and 27 inaproportion depending on the resistance and reactance of each of these.'windings. There willbe a greater current under stator winding 31 thanunder the winding 30 as there are two rotor windings under statorwinding 31 and only one under stator winding 30. As this current willflow at about the same time as the voltage, and as the current producingthe magnetic flux flows at one fourth of the cycle later than thevoltage, the currents in windings 24 and 27 will neutralize the firstpart of the current wave in stator windings 30 and 31 the latter part ofeach wave being left to magnetize the iron. Where the current isgreater, that is under the winding 31, there will be the greater delayin magnetizing the iron. This means that the flux will go first through30 then through 31 and then through 30 in the opposite direction. Togetfrom 30 to 31 it must cross the conductors of the windin 24. Then toget .to 30 in the opposite direction it must continue to cross theconductors of 24 in the same direction of rotation. We then have arotating field which is the condition necessary for starting. The factthat it passes from one end of the machine to the other will notinterfere.

When the motor is up to speed both windings 24 and 27 will share indoing work. This is a great advantage over previous devices using extracoils on the stator for the latter waste power when running unlessmechanically disconnected, which requires objectionable mechanicaldevices.

In theembodiment of the invention shown in Figs. -l-3 inclusive, thedelay in the flux is produced by the contact of the ring 20 with thecore while the ring 18 is insulated therefrom. The portion of the rotoradjacent to the ring 20 will act in the same way as does the structure22 in the embodiment shown in Fig. 4, While the portion of thisstructure adjacent to the ring 18 will act in the manner described forthe structure 21. The setting of the wiring of the stator at an angle asshown in Fig. 3 roduces the same effect as was described or the stators,30 and 31 set at an angle to each other in the embodiment of Fig. 4.

Instead of setting the rotor windings parallel to the axis of the shaftand the stator windings at an angle thereto, the rotor windings may beset at an angle as shown in Fig. 7 and the stator windings may beparallel with the shaft or at an opposite angle as desired. In Fig. 7,the wind- 1ng rods 34 contact on one end of the core with the ring 35and at the opposite end with the rin 36. This latter .end is insulatedfrom t e core in the same manner as the ring 18 in the embodiment shownin Fig. l. The currents produced in the core adjacent to the ring 36 aregraphically illustrated by the lines 37 and these currents act in thesame manner as the currents in the structure 22 of'Fig. 1.

If the two part rotor of the embodiment shown in Fig. 4, is used, thecoils of the stator may be united in one by making each turn cross fromone iron structure to the other asis shown in the drawings in Fig. 6.The two parts of the stator core are designated 38 and 39 and thewindings are designated 40.

The delay in the flux may readily be obtained by using in the rotor coreiron of different magnetic qualities.

Many other embodiments of this'invention might be illustrated here butit is believed that these will be readily evident to any one skilled inthe art in view of the disclosures made in thisapplicatiomand theapplicant does not care to be limited to the particular embodimentsherein shown and described.

IV-hat I claim as my invention and desire to secure by Letters Patentis 1. In an induction motor, the combination'with a secondary membercomprising a magnetic core, conductors providing paths otrelatively highconductivity substantially from end to end thereof, and end rings, oneof which is insulated from said core While theother is in electricalcontact therewith, -of a primary memberhavin means for producingmagnetic fields of w ich the axes at different oints in the length ofsaid secondary memiier have different peripheral displacement relativeto said conductors. 4

I 2. A secondary member for an induction motor comprising a magneticcore, con-' ductors providing paths of relatively high conductivitysubstantially from end to end thereof, and end rings, one of which isinsulated from said core while the other is in electrical contacttherewith.

3. In a device of the class described, a stator, conductors extendingsubstantially from end to end thereof and connected to form a windingtherefor, a rotor comprising a core of magnetic material, insulatedconductors extending substantially from end to end thereof but set at anangle to' the conductors in said stator, a conducting ring at one end ofsaid core in electrical contact with one end of said rotor conductorsand with the core, and a second conducting ring at the opposite end ofsaid rotor from the first ring contacting with the opposite end of saidconductors from the first ring but insulated from said core.

In testimony whereof I afiix my signature in the presence of twowitnesses.

' ALLAN W. FORBES.

Witnesses:

HARTLEY W. BARTLETT, HANNAH M. KENNEDY.

